Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Chromatographic Determination of Glycoalkaloids in Eggplant(Izmir Institute of Technology, 2006) Tek, Neslihan; Tek, Neslihan; Eanes, Ritchie C.Novel modifications were applied to high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) for the separation and quantitation of the steroidal glycoalkaloids (SGAs) solanine, chaconine, solamargine, and solasonine as well as the steroidal glycoalkaloid aglycones (SGAAs) solasodine and solanidine. Because attempts to develop a gradient elution HPLC method were only marginally successfully and non-robust, it was deemed more practical to develop separate HPLC methods for either the SGAs or SGAAs of interest. Furthermore, a novel approach using methanol as a mobile phase modifier was still required to successfully separate solamargine and chaconine. Comparing potential mobile phase buffers, ammonium dihydrogen phosphate was chosen as the most efficient, stable, and economical. Separations were best realized isocratically at a column temperature of 50 °C for the SGAs and either 26 °C or 50 °C for the SGAAs. Progesterone was applied as an internal standard. Effects of pH were also tested. Figures of merit such as limit of detection (LOD), limit of quantitation (LOQ), and linear dynamic range are described herein. Lastly, solid-phase microextraction (SPME) using on-fiber derivatization coupled with GC-MS was investigated for extraction and analysis of these SGAAs. A carbowax divinylbenzene (CW-DVB) coated SPME fiber was the most suitable. Solanidine could be extracted and identified directly using our SPME/GC-MS method while solasodine required a derivatization step involving trimethylsilylimidazole (TMSI). Although initial attempts were qualitatively reproducible, eventual degradation to fibers precluded complete study. Cholesterol as an internal standard was investigated.Master Thesis Development of Inductively Coupled Plasma Spectroscopic Methods for the Determination of Metals in Beluga (delphinapterus Leucas) and Pygmy Sperm (kogia Breviceps) Whale Liver Samples(Izmir Institute of Technology, 2005) Parlayan, Filiz; Eanes, Ritchie C.Inductively couple plasma optical emission spectrometry (ICP-OES) is widely used to monitor elements in biological samples from marine organisms for ecological evaluations. Matrix effects (particularly those related to acid and salt type and concentrations) can present a barrier to the applicability of this instrumental method. To have a better understanding of these effects and to choose a suitable internal standard to correct for the signal variations, a procedure based on Principal Component Analysis (PCA) of the data from an axial-mode ICP-OES instrument with sequential detection was performed. Different from other published studies, it was found that ionic lines were more affected by matrix changes. Elements with high ionization energies and energy sums such as Cd and Zn showed a significant change for signal intensities and calculated concentrations due to the presence of acid, salt, and multielement matrix effects. It was observed that acid has a higher influence on the analyte signal as compared to the "salt-only" case. Furthermore, when several interfering elements were present in the sample, the matrix effect was either enhanced or reduced when compared with a solution containing only a single interfering element. Applicability of the proposed technique for the analysis of whale liver homogenate NIST certified material was investigated. The values of the corrected concentrations were in good agreement with the certified values, confirming the capabilities of the selected internal standards for compensation of matrix effects.